Blackeyed Susan (Rudbeckia hirta)
Formerly Rudbeckia flava, Obeliscotheca flava, Rudbeckia floridana
Rudbeckia hirta, commonly called black-eyed Susan, grows best with at least six hours of direct sun a day, though it tolerates part shade too. It prefers evenly moist soil and is drought tolerant once established. The plant is toxic to both cats and dogs.
Photo: G. Edward Johnson, CC BY 4.0 via Wikimedia Commons
Quick facts
| Light: | Full sun and part shade (full sun preferred)12 |
|---|---|
| Water: | Medium32 |
| Soil: | Well drained, moist and occasionally dry13 |
| Hardiness: | Zones 3a–8b11 source |
| Size: | 2–3 ft (0.61–0.91 m) × 1–2 ft (0.3–0.61 m)271 |
| Growth rate: | Rapid17 |
| Bloom: | Yellow, orange, red and brown13 |
| Cats: | Toxic to cats (1 source) 6 |
| Dogs: | Toxic to dogs (1 source) 6 |
| Native range: | ALA, ARK, CAL, CNT, COL, DEL, FLA, GEO, IDA, ILL, INI, IOW, KAN, KTY, LOU, MAI, MAN, MAS, MIC, MIN, MRY, MSI, MSO, NCA, NDA, NEB, NWH, NWJ, NWM, NWY, OHI, OKL, ONT, ORE, PEN, SAS, SCA, SDA, TEN, TEX, UTA, VER, VRG, WAS, WDC, WIS, WVA, WYO8 |
| Family: | Asteraceae |
How much light does a Blackeyed Susan need?
Give this plant full sun whenever you can. Full sun means at least six hours of direct sunlight a day. It also tolerates part shade. Full sun is the preferred light level for this plant, and part shade is the only other light level listed for it.
How often to water a Blackeyed Susan
Medium water is what this plant needs. It prefers evenly moist soil but tolerates drought and heat once it is established. Its soil is listed as well drained, moist and occasionally dry. Occasionally dry soil is one of three moisture conditions recorded for it, alongside well drained and moist.
Best soil for a Blackeyed Susan
Good drainage is essential for this plant's soil. Clay, loam and sandy soils are all listed as suitable soil types for it. The soil can also stay moist or run occasionally dry. Along with that range, it needs medium water, and it tolerates both drought and heat once it is established. Moist, well-drained conditions across clay, loam or sandy ground all fall within the soil range recorded for this plant. Well-drained, moist to occasionally dry conditions make up the full soil profile recorded for this plant.
Hardiness and temperature
This plant is hardy in USDA zones 3a through 8b. That is the hardiness range recorded for it, from zone 3a to zone 8b. It also tolerates heat, along with drought, once it is established. Within that zone range, it survives outdoors through the winter months.
- Hardiness: Zones 3a–8b1
Fertilizing a Blackeyed Susan
A light, annual feeding schedule works for this plant. That means an application in April and another in September. The September feeding is about a half pound per 100 square feet. Two light feedings a year like this are enough for it. This plant is not fed heavily; the amount applied is described as light in both of those months. That is the full feeding schedule listed for this plant.
- Fertilizer: Light, once a year (Apr, Sep)2
Pruning a Blackeyed Susan
This plant benefits from deadheading, the removal of spent flowers. Deadheading encourages it to rebloom and keeps it looking its best. You can also remove dead growth only, without cutting back live stems. Do this pruning in March. Both of these pruning types are listed for this plant. March is the only month listed for either type of pruning.
- Pruning: Deadheading and Remove dead growth only (Mar)2
How to plant a Blackeyed Susan
Plant it outdoors within USDA zones 3a through 8b. Choose a planting site that gets full sun, or part shade if that is not available. Space plants about 1 to 2 ft (0.3-0.61 m) apart, matching the clump width this species reaches. Plant it into soil that is well drained, moist to occasionally dry.
- Hardiness: Zones 3a–8b1
Winter care
Zone 3a marks the coldest end of this plant's hardiness range. Zone 8b marks the other end of that same hardiness range. In zones 3a to 8b, gardeners can leave this plant in the ground over the winter months. That is the hardiness range recorded for this plant.
- Hardiness: Zones 3a–8b1
Care calendar
| Task | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Fertilize | Fertilize in Apr | Fertilize in Sep | ||||||||||
| Prune | Prune in Mar |
How to propagate a Blackeyed Susan
Propagate this plant from seed or by division. Those are the two propagation methods recorded for this plant. It propagates very easily from seed sown in fall or spring. Division is the other method listed for it. Either way, plant new seedlings or divisions into soil that stays well drained and ranges from moist to occasionally dry. This plant can be propagated by either of those two methods, seed or division.
- Propagation: Seed and division3
Common problems
Slugs and snails, aphids, caterpillars, Japanese beetles, spider mites and rabbits are the pests recorded for this plant. Diseases recorded for it include powdery mildew, southern blight, septoria leaf spot, bacterial leaf spot, fungal leaf spot, stem rot, downy mildew, rust and aster yellows. Rabbits are listed as a pest to watch for, and protecting plants from them is recommended.
| Problem | Kind |
|---|---|
| Slugs and snails | Pest |
| Aphids | Pest |
| Caterpillars | Pest |
| Japanese beetles | Pest |
| Spider mites | Pest |
| Rabbits | Pest |
| Powdery mildew | Disease |
| Southern blight | Disease |
| Septoria leaf spot | Disease |
| Bacterial leaf spot | Disease |
| Fungal leaf spot | Disease |
| Stem rot | Disease |
| Downy mildew | Disease |
| Rust | Disease |
| Aster yellows | Disease |
Is Blackeyed Susan toxic to cats and dogs?
Rudbeckia hirta is toxic to both cats and dogs. The risk comes from a cat or dog eating a large amount of the plant. A large ingestion can cause vomiting and diarrhea in either animal. It can also cause dermatitis. Lethargy has been reported as well. These are the signs reported after a cat or dog eats a large amount of this specific plant. That listing covers both animals under a single toxic rating for this plant. Vomiting, diarrhea, dermatitis and lethargy are the specific signs this source lists for large ingestions by cats or dogs. This page lists the same toxic rating and the same set of signs for cats as it does for dogs.
Pet-safe alternatives
Recommended supplies
- Soil: a free-draining mix, and a pot with a drainage hole.
Questions and answers
- Is black-eyed Susan toxic to cats and dogs?
- Yes, Rudbeckia hirta, also called black-eyed Susan, is toxic to both cats and dogs. Large ingestions can cause vomiting, diarrhea, dermatitis and lethargy in either animal.
- How much light does black-eyed Susan need?
- It grows best in full sun, which means at least six hours of direct sunlight a day, though it also tolerates part shade as a second option.
- How often should you water a black-eyed Susan plant?
- This plant needs medium water and prefers evenly moist soil, but it tolerates both drought and heat once it is established as well.
Sources
- NC State Extension Gardener Plant Toolbox. https://plants.ces.ncsu.edu/plants/rudbeckia-hirta/. Accessed 24 September 2026.
- Clemson Cooperative Extension HGIC. https://hgic.clemson.edu/factsheet/rudbeckia/. Accessed 24 September 2026.
- Lady Bird Johnson Wildflower Center (Native Plant Database). https://www.wildflower.org/plants/result.php?id_plant=RUHI2. Accessed 24 September 2026.
- University of Wisconsin-Madison Division of Extension. https://hort.extension.wisc.edu/articles/prairie-sun-black-eyed-susan-rudbeckia-hirta/. Accessed 24 September 2026.
- Penn State Extension. https://extension.psu.edu/black-eyed-susan-beautiful-and-beneficial. Accessed 24 September 2026.
- Pet Poison Helpline. https://www.petpoisonhelpline.com/pet-safety-tips/quick-spring-refreshers/. Accessed 11 October 2026.
- University of Florida IFAS Extension (EDIS). https://ask.ifas.ufl.edu/publication/FP512. Accessed 24 September 2026.
- Royal Botanic Gardens, Kew (World Checklist of Vascular Plants). https://sftp.kew.org/pub/data-repositories/WCVP/wcvp.zip. Accessed 4 June 2026.
How this page was made
- Written with AI assistance from the sources listed on this page. AI is never the source of a fact.